Organolead compounds and polyurethane foams produced by the use thereof as catalysts



United States Patent 3,547,841 ORGANOLEAD COMPOUNDS AND POLYURE- THANE FOAMS PRODUCED BY THE USE THEREOF AS CATALYSTS Henricus G. J. Overmars, Zeist, Netherlands, assignor, by

mesne assignments, to International Lead Zinc Research Organization, Inc., New York, N.Y., a corporation of New York No Drawing. Original application Feb. 23, 1965, Ser. No. 434,670, now Patent No. 3,417,113, dated Dec. 17, 1968. Divided and this application Sept. 6, 1968, Ser. No. 807,140 Claims priority, application Netherlands, Mar. 2, 1964, 6402097 Int. Cl. C08g 22/40, 22/44; C07f 7/24 US. Cl. 260-25 14 Claims ABSTRACT OF THE DISCLOSURE Monoaryllead trisacylates in which at least one of the acyl radicals is halogen substituted with a halogen of the group consisting of chlorine and bromine. It also discloses a process for making such compounds by reacting an alkylplumbonic acid in a common solvent with heat. The application also discloses a process for making thermostable polyurethane foams by the reaction of at least one polyfunctional isocyanate, and at least one polyhydroxy compound in cooperation with a blowing agent by using as a catalyst one of the halogenated monoaryllead trisacylates as disclosed herein.

The present application is a divisional application of the application Ser. No. 434,670, filed Feb. 23, 1965, issued as US. Letters Patent No. 3,417,113 on Dec. 17, 1968.

The present invention is directed to a process for making polyurethane foams by the reaction of at least one organic polyisocyanate and at least one polyhydroxyl compound having a molecular weight between 400 and 2,000 in the presence of a blowing agent, the step of carrying out said reaction in the presence of a catalytic amount of a compound having the formula:

wherein Ar is selected from phenyl, tolyl, or naphthyl and R, R and R are alkyl radicals having 2 to 18 carbon atoms, at least one of said R, R R being monosubstituted by chlorine or bromine.

More particularly this inevntion relates to novel organolead compounds in which the lead has a valence of 4, and to methods of making same. It also relates to the manufacture of polyurethane foams by the use of said compounds as catalysts, and to the foams so produced.

In brief, my novel compounds may be broadly characterized as the phenyllead trisacylates in which at least one of the acyl radicals is halogen-substituted. Or equally they may be characterized as the fatty acid salts of monoarylplumbonic acid with at least one halogen subsitution for a hydrogen atom in at least one of the fatty acid radicals.

My invention will be best understood from the following detailed description which includes examples of the new organolead compounds and their manufacture, and of the methods of using them as catalysts in the manufacture of polyurethane foams.

Examples I and II which follow directly, relate to methods of making my novel lead compounds.

EXAMPLE 'I 160 grams of phenylplumbonic acid, PhPbOOH, was stirred together with g. of monochloracetic acid in five litres of dry benzene while heating mildly (below 40 C.) until a clear solution was formed. The benzene was removed in vacuo at about 30 C. A light yellow oil having a refractory index of 1.5958 at 200 C. was left. The product was phenyllead tris-(monochloracetate.)

The yield was substantially equal to the theoretical yield. The product showed the following analysis:

Pb content as found 35.61%; calculated: 37.76% CI content as found 17.84%; calculated: 18.65%.

The above reaction may be represented by the equation:

(1) PhPbOOH+ 3ClCH COOH- PhPb OCOCH Cl 2H O This reaction has a broad application, and may be used Whenever it is desired to form a corresponding compound of any halogenated acyl compound. For example, starting with monochloroleic acid, ClC17H33COOH, phenyllead tris(monochlorooleate) may be obtained.

EXAMPLE II Pb content as found: 31.71%; calculated: 31.99% Br content as found: 21.66%; calculated: 25.20%.

The reaction involved may be represented by the following equation:

(2) PhPb( OCOCH 3 +2CH -CHBrCOOH PhP b (OCOCH (OCOCHBrCH 2CH --COOH The same type of reaction as (1 was used to make the following additional compounds:

The same type of reaction as (2) was used to make the following compound:

Percent Pb Percent halogen Calcu- Found lated Found Phenyllcad (diacetate) (alpha'bromoproplonate) 35. 92 37. 36 14. 97

Calculated m The above and similar compounds may be prepared by other reactions, as for example the following:

although this reaction may also proceed:

(4) Pb (OCOCH Cl) +Ph Hg PhPb (OCOCHgCl) +PhHgOCOCH Cl a) where R R and R represent alkyl groups.

Further, the non-halogenated compound may first be made as by reactions (1) and (2), and the halogen atoms then introduced to one or more of the acid radicals.

I have discovered that surprisingly, these novel organolead compounds offer the solution to a number of problems with respect to the production and the properties of polyurethane foams.

Polyurethane foam is obtained by reacting polyfunctional isocyanates with polyhydroxy compounds in the presence of a blowing agent. This blowing agent can be a low-boiling liquid such as one of the freons, lower hydrocarbons, or esters and the like, i.e., the so-called physical blowing agents; and preferably it can also be carbon dioxide, created in situ by the reaction of water with a small part of the polyfunctional isocyanate.

Organometal compounds, as for example, tin dioctoate, are commonly used as catalysts promoting gelation, i.e., the reaction between isocyanate and polyhydroxy compounds. A drawback of a compound of this type is that it is unstable, thereby requiring the use of stabilizers which have drawbacks of their own. Basic metal compounds such as metal carbonates, carboxylates and the like frequently give rise to a hydrolytic degradation of the final product. The well-known cobalt naphthenate gives rise to discoloration, and also requires the additional use of a hydrocarbon solvent, because by itself, it does not readily dissolve in the reaction mixture. It is true that strong bases are extremely active, but for the production of foam they are useless, because it is impossible to control the gelation. Ferric acetylacetonate is effective, but gives rise to discoloration and to an oxidative degradation of the final product.

However, the novel organolead catalysts promote both the reaction already mentioned of gelation, and of CO production, both in the proper sequence. Heretofore, it has been thought that if both reactions were to be carried out at all, it would be necessary to employ separate catalysts for the two reactions, as for example, certain organometal compounds for the isocyanate-polyhydroxy reaction (gelation) and tertiary amines for the isocyanate-water reaction.

In practice, however, it is found that the two catalysts interfere with each other, whereby the use of such an overall process has been extremely limited.

A great disadvantage of tertiary amines is that, as a result of their volatility, they lend an unpleasant odor to the final product. In addition, they give rise to undesired erties. They generally require high reaction temperatures and are not very active, even to the point of being practically unfit for use in reactions with aliphatic isocyanates. There is thus a need for a single catalyst which will not only bring about a satisfactory isocyanate-polyhydroxy reaction, but also a satisfactory isocyanate-Water reaction, and in such a way so as to have each of these reactions catalyzed at the right time and in the right manner. A catalyst which would strongly catalyze the CO formation before the formation of polyurethanes was well on its way, is no more satisfactory than a catalyst which would have substantially completed the polyurethane formation before the formation of CO gets started. Moreover, there should intervene a certain lapse of time between the mixing of the components and the beginning of foaming, thus facilitating the use of the usual spray nozzles, and with the overall result of a fine and regular foam structure.

Thus a known catalyst, tin dioctoate, is found to be much too slow in catalyzing the CO formation, whereas, another known catalyst, triethylenediamine is found to be much too slow in catalyzing the gelation reaction. Nor is it possible to render these catalysts suitable for the twofold purpose by changing the concentrations used. It is indeed possible to slow down the formation of CO with triethylenediamine by using a lesser concentration of catalyst, but this is of no avail because in that case gelation is retarded even more. If the concentration of tin dioctoate is increased, the formation of CO is accelerated, but so is the gelation to a much higher degree.

A method for testing the effect of catalysts on gelation is the following:

5 grams of a branched polyether (polyoxypropyleneglycol having a KOH index of 55 and a molecular weight of about 3000) is mixed with 50 mg. of the substance to be tested. Subsequently, 0.4 cc. of toluenediisocyanate 2-4 derivative and 20% 2-6 derivative) is admixed thoroughly at 20 C. The time is measured in minutes elapsing until the mixture has gelated.

Known compounds such as diphenyllead dilaurate, dibutyllead dilaurate, diethyllead maleinate, tributyllead laurate, triphenyllead acetate, tetraphenyllead, and hexa phenyllead appeared in this test to show gelation times of more than 450 minutes, which is much too long.

The new organolead compounds according to this invention show short gelation times, on the order of a feW minutes to about one half hour. This is likewise true even though different hydroxy compounds, different mixing ratios, and different isocyanates are used, and whether the process be carried out in the laboratory or on a commercial scale.

A blank test, i.e., without any catalyst, showed a gelation time far too great to be practicable.

The following method for testing the effect of catalysts on the formation of CO in situ, is given:

80 mg. of the substance to be tested is mixed with 4 cc. of tetrahydrofuran and 4 cc. of dimethylcellosolve in which 228 mg. of water has been dissolved in a flask filled with carbon dioxide gas. The flask is connected to a gas burette and .2 cc. of toluenediisocyanate (80% 2-4 and 20% 2-6 derivative) are added by means of an injection needle while stirring, all of this at 30 C. The time in seconds necessary for the formation of cc. of CO is then measured.

Compounds such as diphenyllead dilaurate, tributyllead acetate, tetrabutyllead, as well as tin dioctoate, appear to catalyze the CO formation much too slowly (times on the order of 200-600 seconds in the abovequoted test), whereas with the novel organolead compounds according to the invention, the times are on the order of 14-15 seconds. A blank test yielded less than 100 cc. of CO after 600 seconds.

Further, the catalysts according to the invention are found to be suificiently effective even at concentrations lower than, for instance, 1% calculated on the weight of the reaction components. This is in contrast to many known catalysts which rapidly become ineffective as the concentration decreases. The amount of catalyst to be used in order to obtain a good foam can easily be established by a practical test. This is dependent both on the manner and on the mechanical device with which the foam is produced. Quantities on the order of from 0.05 to percent by weight have been found useful; higher concentrations can be used if more rapid foam formation is sought, whereas lower concentrations can be used if a slower rate is permissible, a foam of good structure and good mechanical properties being had in either case. The control of foam flexibility may be had by the choice 0 the reaction components.

Besides toluenediisocyanate, other aliphatic or aromatic isocyanates are highly suitable for use in the present process, such as polymethylenepolyphenylisocyanate, diphenylmethanediisocyanate and the like, as are mixtures of other known isocyanates. The same is true of the polyhydroxy compounds.

In the formation of foam according to my invention, other known substances functioning as stabilizers, combustibility and/ or infiammability retardants, filling agents, pigments, dyes, silicone oil, etc., also other catalysts may be used if desired.

While permitting the same degree of control of conditions as obtain in the prior art, my improved process is further characterized by the fact that other things being equal, a somewhat longer time is required for the reactions to go to completion. This is to be regarded as an advantage since less risk of premature gelation and foaming up will be had.

The apparent specific weight (kilogram per cubic meter of foam) can be controlled within wide limits by a suitable choice of the concentrations, inter alia of water. It is very simple to attain apparent specific weights between 0.01 or lower, and 0.06 and higher. Another advantage of the catalysts according to the invention is that, as already stated, they readily dissolve in the polyhydroxy compounds used for the preparation of polyurethanes especially in the widely used polyethers. Very useful polyhydroxy compounds are those polyethers which contain hydroxyl groups, such as polyethylene glycols and polypropylene glycols with a molecular weight ranging from about 400 to about 2000, and products obtained by addition reactions of polyalkylene oxides (such as polypropylene oxide) with triols such as glycerol or trimethylol methane. These and other useful ingredients for the production of polyurethane foams are described by Bernard A. Dombrew in his book Polyurethanes," New York.

The preparation of polyurethane foam with the novel organolead compounds will now be illustrated in the following examples:

EXAMPLE III 100 grams of a polyoxypropylenetriol (molecular weight 2000) was mixed with 1% of silicone oil and 0.4% by weight of phenylleadtris(omegabromoundecylate), while stirring constantly. After some time, 4 grams of water was added and subsequently, at a quick rate, 44 grams of a mixture of 2.4 and 2.6 toluenediisocyanate in a ratio of 80 to 20. After more seconds of stirring without external heat being applied, the mixture was poured out into a paper cylinder in which some 40 seconds later, a very rapid foaming took place. This gave rise to a polyurethane foam of regular structure and an apparent specific weight of 0.027.

The swelling in benzene amounted to 33%, and in acetone to .25

EXAMPLE 1V Example III was repeated, but this time with 0.3% by weight of phenyllead tris(betachloropropionate). The foam obtained had an apparent specific weight of 0.036.

EXAMPLE V Example III was repeated, but this time with 0.3% of paratolyllead tris(betachloropropionate). The foam obtained had an apparent specific weight of 0.035.

EXAMPLE VI Example III was repeated, but this time with 0.3% of betanaphthyllead tris(betachloropropionate). The foam obtained had an apparent specific weight of 0.037.

In addition to the advantages already stated for the new compounds in the manufacture of polyurethane foams, a still further advantage of great importance remains to be stated. As of now, polyurethane foams suffer from the drawback that they deteriorate with age, particularly when stored. A test for this is the so-called accelerated aging test which consists in heating the foam in the air to a comparatively high temperature, whereupon disintegration takes place. To make the test quantitative, the disintegrated foam is extracted with a suitable solvent, e.g., methylethylketone, the extract concentrated to dryness by evaporation, and the residue weighed. The greater the amount by weight of the residue, the greater the disintegration that is produced. Present attempts are made to slow the aging process by the use of so-called stabilizers, of which catechol, butyl catechol, tartaric acid, are examples. The use of these substances, however, gives rise to certain drawbacks, as for example: tartaric acid slows the foam reaction, and impairs the foam structure; catechols produce undesirable odors and discolorations, particularly since they exude from the finished foam, and are subject to evaporation.

I have now discovered that my improved catalysts like- Wise function as stabilizers to the end that the use of extraneous compounds for the purpose of stabilization is no longer required. Attention is drawn to the following examples which illustrate the stabilizing effect of the new compounds.

EXAMPLE VII Examples III and IV were repeated as above set forth, and Example III again repeated but with a non-halogenated catalyst viz., phenylleadtriacetate. The above aging test was then run on the products obtained, i.e., the fresh foam was heated to C. for 5 hours and methylethylketone extracted. The results were as follows:

Residue of the extract in percent Before heating Catalyst After heating Phenyllead tris(betachloropropionate) Phenyllead tris(ornegabromoundeeylate) Phenylleadtriacetate Paratolyllead tris- (betachloropropionate) Betanaphthyllead tris- (betachloropropionate) While compounds of the invention having three diflerent acyl groups attached to the lead atom may be used, with at least one of such groups halogenated, thus far we have found it easiest to have at least two of such radicals the same.

While a complete explanation of the action of the new catalysts remains to be discovered, so far it appears that the mobility of the halogen atom is a factor; thus if all the halogen atoms are attached to the phenyl nucleus where they are more firmly bound, the beneficial effect is not had.

It will be understood that in the light of the foregoing disclosure, other and analogous compounds will suggest themselves to those skilled in the art, which will be within the spirit of my invention.

In the claims, the term halogen is to be restricted to include chlorine and bromine only.

I claim:

1. A process for making thermostable polyurethane foams by the reaction of at least one organic polyisocyanate and at least one polyhydroxyl compound having a molecular Weight between 400 and 2,000 in the presence of a blowing agent, the step of carrying out said reaction in the presence of a catalytic amount of a compound having the formula:

wherein Ar is selected from phenyl, tolyl, or naphthyl and R, R and R are alkyl radicals having 2 to 18 carbon atoms, at least one of said R, R and R being monosubstituted by chlorine or bromine.

2. The process according to claim 1 in which sufiicient water is present so as to result in the formation in situ of the blowing agent CO by the reaction of water with a small part of the organic polyisocyanate.

3. The process according to claim 1 wherein the group Ar is ph'enyl and R and R are alike and halogen-substituted with chlorine or bromine.

4. The process according to claim 1 wherein the group Ar is phenyl, and R, R and R are alike and halogen substituted with chlorine or bromine.

5. The process according to claim 1 wherein the group Ar is phenyl, and R and R are alike and R is halogensubstituted with chlorine or bromine.

6. The process according to claim 1 wherein the catalytic compound is phenyllead tris(beta-chloropropionate).

7. The process according to claim 1 wherein the catalytic compound is phenyllead tris(omega-bromoundecylate).

8. The process according to claim 1 wherein the catalytic compound is phenyllead tris(monochloroacetate).

9. The process according to claim 1 wherein the catalytic compound is phenylleadacetate bis(alpha-bromopropionate).

10. The process according to claim 1 wherein the catalytic compound is phenyllead tris(alpha-bromopropionate).

11. The process according to claim 1 wherein the catalytic compound is phenyllead tris(gamma-chlorobutyrate).

12. The process according to claim 1 wherein the catalytic compound is phenyllead (diacetate) (alpha-bromopropionate).

13. The process according to claim 1 wherein the catalytic compound is paratolyllead tris(beta-chloropropionate).

14. The process according to claim 1 wherein the catalytic compound is beta-naphthyllead tris(beta-chloropropionate).

References Cited UNITED STATES PATENTS 2,985,673 5/1961 Convery 260408 3,347,804 10/1967 Buckley 2602.5 3,385,807 5/1968 Herdlein et al. 260-25 DONALD E. CZAIA, Primary Examiner F. E. McKELVEY, Assistant Examiner US. Cl. X.R.

H050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,547,841 Dated December 15, 19 70 Inventor(s) Henricus G. J. Overmars It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 24, "37.76" should be 36.76--;

Column 2, line 32, "sq." should be aq.-.

Signed and sealed this 29t ;h day of June 1971.

(SEAL) Attest:

EDWARD M.FIETCHER,JR. WILLIAM E. SCHUYLER, J'I Atteatzing Officer Commissioner of Patent: 

